Oxidation of a naphthyl dialkyl methine



Patented Oct. 20,

This invention relates to thyl dialkyl methine to ineihydroperoxide-,- i= e. bon of the formula x1 A'rIoN or? George G.

fin, Morristown, N311} ical & Dye Corporatio poration of New York N 0 Drawing. Application i'zAPHTHYL DIALKYL MEI-,HINEm Serial No.

Lara the corresponding I'meth'- oxidation of a hydrocar- CHRR to a hydroperoxide of the formula 0 0 OH) R R Where R, and R represent alkyl radicals, the

same or different, such In particular, our in tion of the lower (Cs-Cs as methyl, ethyl, etc.

vention relates to oxidaalkyl group) alphaand beta-alkyl naphthalenes of the above structure,

such as alphaand beta-isopropyl naphthalene.

The discussion which follows refers specifically to isopropyl naphthalenes, but it is to be understood that such reference is by way of illustration only and that ou thereto, but includes invention is not limited oxidation of naphthyl. di-

alkyl methines generally, including sec. butyl,

sec. amyl, sec. hex naphthalenes.

Oxidation of alk spondin hydroperoxide because among ides are conver ing naphthols mation of the yl, sec. heptyl, sec. octyl, etc.

yl naphthalenes to the corres is of technical interest other reasons these hydroperoxtible to valuable products includand other useful products. Forhydroperoxides by oxidation of the appropriate alkyl naphthalene proves difficult,

however. So far as we the present invention is the firs to form desired hydro proportions of by-produ are aware, the process of t known process peroxides without large ct.

The difiiculties in forming hydroperoxides of alkyl naphthalenes are a with a marked instability ides, which decompose und ditions and form by ing products, etc. isopropyl naphthalen known heavy metal even at relativel 45 C., more by-produc least when hydroperoxi as much as about 20-22 tion mixture.

pparently connected of these hydroperoxer usual reaction coneven very by weight, of talysts such as stated to form, tures such as t than hydroperoxide at de concentrations reach by weight of the reac- 3 Claims. (Cl. 260

m assigiiors' to Allied Ch formed in t Will am New York,

fi'fie 23, 1951, 233,246

g agent. The following our invention, but our ereto.

.-Beta -isopropyl naphthalene was prepared by alkylation of naphthalene at 80 C. with isopropyl chloride in the presence of aluminum chloride catalyst, and was treated before oxidation by decolorizing with charcoal and contacting with alkali pellets over which it was stored until withdrawn for use.

Air was bubbled through the isopropyl naphthalene thus prepared, in which was suspended about 1% by weight of reaction vessel at 40 C. at a rate of 10 liters of air per hour per 15 cc. of reaction mixture. Dispersion of the catalyst was maintained by the air bubbles. Oxidation proceeded at a rate of about 0.18 weight percent of hydroperoxide he reaction mixture per hour until eight percent hydroperoxide concenreached. Thereafter oxidation rates about 13 w tration was fell slowly.

Up to concentration of about 17 weight percent hydroperoxide in the reaction mixture, hydroperoxide was the only product detectable by infra red spectrographic analysis. Thereafter small amounts of ketone were formed, about 2 weight percent of ketone at 20 weight percent hydroperoxide concentration and 4 weight percent of ketone at 22 weight percent hydroperoxide concentration.

When temperatures about under otherwise the conditions ab considerably larger proportions 0 formed but the tained still exc obtained.

Suitable temperatures for oxidations by our process are usually between about room temperatures (25 C.) and about 75 0., optimum temperatures for oxidation of beta-isopropyl naphthalene being about 40 C. Optimum temperatures with other alkyl naphthalenes depend upon the ease of oxidizing these and the stability of the hydroperoxide products; they lie between the reaction temperature of the hydrocarbon and the decomposition temperature of the hydroperoxide in solution in the hydrocarbon, which temperatures can readily be ascertained for any particular case by routine experiments.

C. were used ove described. I ketone were proportions of hydroperoxide obeeded the proportions of ketone anaphthyl dialkyl tal oxygen, e-

lead dioxide powder, in a Suitable quantities of catalyst are in the usual ranges for catalyst materials, e. g. between about 0.1% and about 10% by weight. Larger amounts can be used if desired.

Pressures can be atmospheric or higher if desired. Suitable sources of elemental oxygen include purified oxygen, air, off gases from an oxidation stage employing the present process, etc.

Continuous operation can be employed, e. g. a reaction mixture can be maintained at hydroperoxide concentrations corresponding to maximum reaction rates, such as 10-15 weightpercent hydroperoxide concentrations, by continuous withdrawal of reaction mixture and replacement thereof with fresh and/or recycled hydrocarbon and catalyst.

We claim:

1. Process of oxidizing a naphthyl dialkyl methine to the corresponding methine hydroperoxide, which process comprises contacting said methine in liquid phase with elemental oxygen in presence of lead dioxide catalyst, and terminating the oxidation and recovering products at a stage when analysis of the products shows hydroperoxide preponderating heavily over byproducts.

2. Process as defined in claim 1, wherein hydrocarbon oxidized is beta-isopropyl naphthalene, air is the source of elemental oxygen, and temperatures are between about room temperatures and about 75 C.

3. Process as defined in claim 2, wherein temperatures are about 40 C. and quantitie of catalyst are about 1% by weight of the reaction mixture.

GEORGE G. JORIS. WILLIAM D. GRIFFIN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,924,786 Hartmann et a1. Aug. 29, 1933 2,475,605 Prutton et a1. July 12, 1949 2,548,435 Lorand et a1 Apr. 10, 1951. 

1. PROCESS OF OXIDIZING A NAPHTHYL DIALKYL METHINE TO THE CORRESPONDING METHINE HYDROPEROXIDE, WHICH PROCESS COMPRISES CONTACTING SAID METHINE IN LIQUID PHASE WITH ELEMENTAL OXYGEN IN PRESENCE OF LEAD DIOXIDE CATALYST, AND TERMINATING THE OXIDATION AND RECOVERING PRODUCTS AT A STAGE WHEN LANALYSIS OF THE PRODUCTS SHOWS HYDROPEROXIDE PREPONDERATING HEAVILY OVER BYPRODUCTS. 